Proteins are polymers of the bifunctional monomer, amino acids. The twenty common naturally-occurring amino acids each contain an α-carbon, an α-amino group, an α-carboxylic acid group, and an α-side ...Proteins are polymers of the bifunctional monomer, amino acids. The twenty common naturally-occurring amino acids each contain an α-carbon, an α-amino group, an α-carboxylic acid group, and an α-side chain or side group. These side chains (or R groups) may be either nonpolar, polar and uncharged, or charged, depending on the pH and pKa of the ionizable group.
